Abstract ID: A28
Abstract Title: Psoas compartment block with additional sciatic nerve block for total knee joint replacement in 391 consecutive patients
Poster Type: Either
ABSTRACT BODY
Introduction:
Psoas compartment blocks (PCB) have been increasingly applied for postoperative pain relief following knee or hip surgery. For intraoperative anesthesia PCB is mostly performed in combination with general (GA) or spinal anaesthesia (SA). The underlying reasons is the incomplete block of the operation site as well as poor tolerance of tourniquet pain with lumbar plexus block alone. With an additional sciatic nerve block, however, total knee athroplasty should be possible without additional GA. A further reason may be that due to anatomical variations of lumbar plexus, a certain percentage of block failure is common. In our institution the combination of SB and PCB is the standard anesthetic technique for TKJR. The purpose of the underlying study was to evaluate the efficiency and safety of PCB and SCB without additional GA for total knee joint replacement (TKJR) and to identify causes of block failure.
Materials and Methods:
The records of 391 consecutive patients undergoing TKJR with tourniquet application in combined PCB and SCB were examined. All blocks were performed under the supervision of two experienced anesthetists, mostly by means of ultrasonic guidance with additional peripheral nerve stimulation (PNS). There were two analgesic regimen used: ropivacaine 0.5% 100mg and mepivacaine 1% 200mg or ropivacaine 0.375% 75 mg and prilocaine 1% 200 mg by personal preference of the anesthetist. If pain occurred during surgery at the site of surgery due to incision or from tourniquet additional i.v. application of 1µg/kg fentanyl was given. If pain persisted additional general anesthesia (GA) was performed. Need for additional GA or i.v. fentanyl was considered as block failure. Multivariate linear regression analysis was performed to identify causes of block failure.
Results:
Identification of the SCN was successful in all patients. In 2.5% of the patients identification of the lumbar plexus by PNS was not possible, hence alternative anesthetic procedure was chosen or the block was performed by ultrasonic guidance alone. In 2.3% of patients additional intravenous opioid analgesia was required for moderate pain. In 11.7% of patients there was pain during incision or due to tourniquet application and GA was performed. In one patient there was a misplacement of the PCB catheter in the subarachnoid space (previously reported) and in one patient there was an unintended intravascular application of LA with a short loss of consciousness. Both patients recovered without sequelae. Both complications happened in difficult anatomical conditions. Bleeding complications or unintended renal punctures were not observed. Multivariate regression analysis (r2=0.161) revealed the following risk factors for block failure: height (beta coefficient 0.245), duration of block performance (0.237), weight (0.184), history of rheumatism (0.118). The local anesthetic used did not influence block success.
Discussion:
In 88.3% of patients the combination of PCB and SCB provided sufficient quality of intraoperative analgesia during TKJR without additional GA. Technical difficulties during block performance in particular obesity as well as a history of rheumatism may be risk factors for block failure.
ATTACHED FILES
Reg Anesth Pain Med 2004; 29(2):A28